Seeking for help

I just came to Japan 2 days ago.Although,this is not my time here but I've never lived here. I usually came on a visiting visa but now I have 5 yrs resident visa.
I'm having a problem to sign a contract with my current unlock iPhone 5 which i brought from korea. I was told that i need to get a new phone from any of the Japanese company like SoftBank,AU or Docomo before I could get a contract.
I was hoping to go on a contract with my current iPhone 5...Can anyone let me know how this thing work Any advise will be highly appreciate.
Thanks.

You'll be better off looking at 3rd party carriers like B-mobile as the first party carriers either won't give you a contract, or charge a premium for one if you don't purchase a phone through them as well.

http://www.bmobile.ne.jp/lineup.html

The question is if your current cell phone even works with JP cards. I have my (European) phones unlocked as well and when I put a JP card in it, it wouldn't even load (it was like if there was no SIM inserted). So I have a local phone now (and according to my colleagues, this is it and they were surprised that in Europe, you can put pretty much any sim to your phone as long as it's unlocked). Perhaps someone here can clarify but this is my experience from beginning of this year. If you have a chance, I suggest you ask someone you know to lend you their card and see if it works in your phone or not to confirm the above hypothesis (I tried with samsung and HTC).

I have my (European) phones unlocked as well and when I put a JP card in it, it wouldn't even load (it was like if there was no SIM inserted).

What kind of card did you try? With a card from a "virtual" carrier like b-mobile, it should work unless your phone is very unusual (BlackBerry?).

Thanks guys for your help..So far, I have not try any Japanese SIM card on my phone. My point is most company here,like Au, Docomo and SoftBank reject to sign me up on a contract with my brand new iPhone 5 simply because it was not purchase from their company.
So what question is. Does anyone know any other company that accepts foreign iPhone. I don't wanna buy another iPhone while i already have one and i wanna go on monthly plan rather prepared system. Still new here maybe that's why the whole thing still look strange..
Thanks.

I will check the b-mobile. I never heard of that.. Are they also into monthly plan system or just prepaid only.

OBJ2008: it's the first time I hear about virtual carrier in Japan, too. Definitely worth a try.

Firas: NTT or Softbank. Everyone in the office uses one of the three main carriers. Good to know there are other options in Japan, too. As I wrote, phones tried were samsung and htc.

So what question is. Does anyone know any other company that accepts foreign iPhone. I don't wanna buy another iPhone while i already have one and i wanna go on monthly plan rather prepared system.

Please read my first post which addresses those questions. Note that it may be cheaper overall to sell your old phone and enter into a new contract.

Are they also into monthly plan system or just prepaid only.

Depends on what you need. If you want voice + data then its essentially monthly. Data only plans are prepaid.

Just a Guest,

If you're coming from Europe then the first thing to check is if your phone supports Japan's version of 3G. If so you should be good to go. GSM only phones are not supported.

One of the phones was this one:
http://www.gsmarena.com/samsung_galaxy_mini_s5570-3725.php

The HTC was much newer, Desire Dual Sim but I don't know which one, there are many code names for the Desire line. I was told by my JP colleagues that it's normal that it does not work with their sim cards so I simply went ahead and got a NTT Docomo phone along with the subscription.

It's hard to say, because those phones should work. It could be an incompatibility with the SIM cards you tried to put in, and you'd need to know your friends plan, what device the sim came from, etc. But it probably doesn't matter anymore since you went with a JP phone/contract.